This invention relates generally to color printing apparatus that performs color printing utilizing a multiple color ribbon that has sequentially arranged thereon a plurality of sets of different colored ink regions and, more particularly, to an ink ribbon positioning system for positioning the desired color of the colored ink region adjacent a printer head for printing.
2. Description of the Background
There is known color printing apparatus that produces a printed color image or printed characters on a printing paper or film or the like. Such color printers have found applications in various fields, for example, in a video printer that can produce a color still image based on a color video signal, such as a color television signal or a color video signal from an electronic still camera, or a thermal printing word processor that has an image scanning function as well. This type of color printing apparatus typically employs a color ink ribbon that is formed of a plurality of colored ink regions generally arranged as sets of colors that are then sequentially arranged along the length of the ribbon. In one proposed color video image printer the color ink ribbon is generally provided with ink regions containing sublimation dyes of yellow Y to produce yellow color images, magenta M to produce a magenta color image, and cyan C for producing a cyan color image as well as black B. Thus, it is seen that the additive color process is being carried out. Generally these ink regions bearing the above four colors are formed in a series, always in the same order, on the elongated strip of the ribbon with each series being successively repeated over the length of the ribbon. In order to enable the color printer to position the desired color of the ink region in opposition to the printer head to form the image on paper or the like, the color ink ribbon is also provided with a number of indicating or marker blocks that can be detected to determine the color presently aligned with the printer head. It should be noted that such printer heads are typically thermal printer heads when utilizing the sublimation dyes described above.
One example of a color ink ribbon as described hereinabove is shown in U.S. Pat. No. 4,558,329 issued Dec. 10, 1985 and assigned to the Assignee hereof. In this patent, a color ink ribbon is proposed for a thermal-transfer printing operation that can produce a hard copy of a still picture, such as might be produced by a video camera or a television picture image or the like. In this patent the color ink ribbon has a plurality of thermally transferrable ink regions of different colors in a predetermined arrangement and with a corresponding plurality of ink region indicator marks. Such indicator marks are typically marker blocks formed on the base material of the ribbon and contain a dispersion dye, binder, and pigment that is thermally stable and have light absorbing properties for absorbing infra-red light. These marker blocks are disclosed as being formed simultaneously with the formation of the actual various colored ink regions of the ribbon.
The colored ink ribbon described in this patent and the associated printing apparatus shown therein have been found to adequately produce color prints, however, as seen in that patent there is the requirement to provide the ink region indicator marker blocks for each ink region in order to permit precise positioning of the colored portions of the ribbon relative to the thermal print head at the time of forming the image. Although such system does produce acceptable images, there are the drawbacks that a substantial amount of material for the ink region marker blocks is required and also the manufacturing time required to produce the color ink ribbons is increased, even when simultaneous processing is provided relative to the formation of the color ink regions. Thus, the production cost of the color ink ribbons is increased by the requirement for the marker blocks at each of the colored ink regions on the ribbon.